I'm completely with robgil - you paid a company to recommend and install a heating system. That system isn't doing its job adequately and they have a responsibility to sort that out.
I had a similar problem with my new heating system - the calculations indicated the system installed should be just adequate but in practice the heat loss of the building was higher than their simple calculation indicated, even the SAP calcs done for the building control was under estimating the heat load by a substantial factor. In the end the calculations were their problem, not mine - I'd paid them to spec and install adequate heating and that was the contract. They were the experts and I was the customer, I hadn't chosen a cheaper option or ignored their advice.
The solution was to add a second heat source as powerful as the first. Having shivered my way through last winter I can happily say that with more input the underfloor and rads are keeping us nice and warm this year despite the weather outside.
I have legal cover with my home insurance that covered the potential cost to me of legal action which may have been a deciding factor in the negotiations.
It took some strong conversations to get the system uprated at their cost, but in the end it was their problem and they fixed it for which I'm very grateful.
On the other points.
If the barn is noticeably colder on windy days then "ventilation heat loss" is a significant factor and draught proofing is likely to have a significant effect.
Plasterboarded buildings are often very leaky compared with wet plastering. One way to check for this is to turn off the power and unscrew the socket plates on a couple of power points on exposed external walls. If you can feel a cold draught then you are probably living in a plasterboard tent dot and dabbed onto leaky brick (?) walls. The solution to this will be to take down the plasterboard, reline with insulation, reboard and replaster or compensate by adding more heat.
I know of a listed barn conversion, with powerful oil boiler and underfloor heating. The listing prevents insulating the inside or outside of the walls and when the wind really blows then the heat is literally blown out of the building. There is really nothing to do about this
Check for obvious draughts around windows, doors etc. and fix them too. Also check that the pipes feeding the radiators are insulated where they run through floor voids etc. where the heat isn't needed.
In that vaulted room it might be worth looking at installing a ceiling fan to push warm air back down into the room.
Good luck!
I had a similar problem with my new heating system - the calculations indicated the system installed should be just adequate but in practice the heat loss of the building was higher than their simple calculation indicated, even the SAP calcs done for the building control was under estimating the heat load by a substantial factor. In the end the calculations were their problem, not mine - I'd paid them to spec and install adequate heating and that was the contract. They were the experts and I was the customer, I hadn't chosen a cheaper option or ignored their advice.
The solution was to add a second heat source as powerful as the first. Having shivered my way through last winter I can happily say that with more input the underfloor and rads are keeping us nice and warm this year despite the weather outside.
I have legal cover with my home insurance that covered the potential cost to me of legal action which may have been a deciding factor in the negotiations.
It took some strong conversations to get the system uprated at their cost, but in the end it was their problem and they fixed it for which I'm very grateful.
On the other points.
A wet plastered, wallpapered room is going to have a much more air tight seal than the same room with exposed brick. There is a limited impact from the insulation effect of the plaster but sealing the wall against draughts has a big impact.JoceAndChris said:What's warmest is a series of small, properly plastered rooms, with proper celings - and I swear a wallpapered room is intrinsically warmer than an exposed brick one.
If the barn is noticeably colder on windy days then "ventilation heat loss" is a significant factor and draught proofing is likely to have a significant effect.
Plasterboarded buildings are often very leaky compared with wet plastering. One way to check for this is to turn off the power and unscrew the socket plates on a couple of power points on exposed external walls. If you can feel a cold draught then you are probably living in a plasterboard tent dot and dabbed onto leaky brick (?) walls. The solution to this will be to take down the plasterboard, reline with insulation, reboard and replaster or compensate by adding more heat.
I know of a listed barn conversion, with powerful oil boiler and underfloor heating. The listing prevents insulating the inside or outside of the walls and when the wind really blows then the heat is literally blown out of the building. There is really nothing to do about this
Check for obvious draughts around windows, doors etc. and fix them too. Also check that the pipes feeding the radiators are insulated where they run through floor voids etc. where the heat isn't needed.
In that vaulted room it might be worth looking at installing a ceiling fan to push warm air back down into the room.
Good luck!